Few literary innovations have exercised as much influence upon Christian attitudes toward internal diversity as has the practice of organizing the names and alleged misdeeds of rival teachers into heresy catalogues. For two millennia, followers of Jesus have employed the heresy catalogue as a powerful weapon in internal struggles for legitimacy, authority, and supremacy. Despite its enduring popularity and influence within the Christian tradition, the heresy catalogue remains an underappreciated polemical genre among historians of early Christianity. Guilt by Association explores the creation, publication, and circulation of heresy catalogues by second- and early third-century Christians. Polemicists made use of these religious blacklists, which include the names of heretical teachers along with summaries of their unsavory doctrines and nefarious misdeeds, in order to discredit opponents and advocate their expulsion from the authentic Christianity community. The heresy catalogue proved to be especially effective because it not only recast rival teachers as menacing adversaries, but also reinforced such characterizations by organizing otherwise unaffiliated teachers into coherent intellectual, social, and scholastic communities that are established and sustained by demonic powers. Geoffrey Smith focuses especially on the earliest Christian heresy catalogues, including those found within the works of Justin, Irenaeus, and Hegesippus, to shed new light upon the complex process through which early Christianity took shape.